I don't know why people keep repeating this. Magnetic connector =/= MagSafe easy tear away cable from the mid 2000s.
True, the iMac reviews show it actually being quite hard to pull out. In which case, what's the point?
(Ans: #1 design priority for the iMac was clearly to make it unnecessarily thin so it didn't have enough depth to hold a PSU or a good old figure-8 connector).
But ooh, look, it's got a magnet, shiny, it must solve a problem we didn't know we had... (let's see if Apple have learned how to make captive cables that don't disintegrate after a year of being kicked around on the floor... but then strain relief sleeves are sooo ugly and don't have magnets in them...)
The current enclosure had plenty of space to incorporate a hot Intel processor, a power supply, an optical drive
and a spinning rust HD, yet it's still small enough to hide behind a display on a vesa mount, or put in a high density rack. If the new chip is feeling a bit lost then, instead of making it smaller, why not stick
more stuff in there... like a slot for an extra SSD?
(Oh, and getting an Ethernet cable onto my desk was a problem I solved sometime last century - and for every user who's ethernet port is next to their mains socket, there's another who's cable goes to a switch or router at desk level...)